Re: [gpsd-users] possible week rollover problem

[Gary E. Miller]

Yo Paul!

On Tue, 25 Aug 2015 13:44:04 -0400
Paul Fox <address@hidden> wrote:

> i've been seeing bad dates from gpsd which seem to indicate a week
> rollover issue.  i've been running gpsd 3.9, which i realize is out of
> date, but which i think is more recent than most "week
> rollover"-related commits i could see in the git log.  (i've now
> upgraded to gpsd 3.15, so i'll see if the problem described below
> reappears.)

Likely no change.

> i have two BU-353 usb dongles:  one older (sirfstar 3?), the other a
> newer S4 with a sirfstar 4.  (yes, i've read the FAQ, and it's slow
> to acquire sometimes, but i needed something in a hurry at the
> time.)  they both exhibit similar date issues with gpsd. 
> unfortunately, it's hard (because of the binary protocol) for me to
> trivially check them against something other than gpsd.

So just put them in NMEA mode.
 
> what i've observed:
What we really need is gpsd raw logs, or raw GPS output that we can look at.

> if this is a known issue with the sirf chipsets,

Pretty much all GPS can lose the GPS epoch.  Usually when the internal GPS
battery is dead, but your units sound to new or that.  But most GPS
can report bad time until they have had a good sky view for 30 minutes.

So only worth looking at if the bad time persisted after 30 mins of
valid fixes.

> then i'll probably
> put a bandaid into my application and call it a day.  but i'm also
> happy to do more debugging/logging, or add instrumentation, if that
> would be helpful.

Yup, that would be helpful.  Also, when reporting gpsmon results, you
need to say whether it was in standalone or slave mode.  In standalone
mode gpsmon talks directly to the GPS, in slave mode it just reports
what gpsd is seeing.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1(541)382-8588

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